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Issue 7, 1974
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On the mechanism of ring metallation of aromatic compounds. Metallation of thiophen by lithium and by lithium dihydroarylides

Abstract

Thiophen is metallated by lithium metal or lithium dihydroarylides in the 2-position. Product yields and magnetic titration results indicate that the transformation is a two electron process. The process becomes one-electron when the reaction is carried out in the presence of 1,1-diphenylethylene or α-methylstyrene. Paramagnetic decay in solutions of various lithium dihydroarylides and thiophen is of the first order. The log k1 values correlate with the π-energy change of the reaction ArH[graphic omitted] ArH + e. A mechanism for the metallation of thiophen by lithium dihydroarylides involving an unstable thiophen radical-anion intermediate is suggested. It is also suggested that metallation by conventional lithiating agents takes place through the intermediacy of a radical-anion.

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Article information


J. Chem. Soc., Perkin Trans. 2, 1974, 745-748
Article type
Paper

On the mechanism of ring metallation of aromatic compounds. Metallation of thiophen by lithium and by lithium dihydroarylides

C. G. Screttas, J. Chem. Soc., Perkin Trans. 2, 1974, 745
DOI: 10.1039/P29740000745

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